There are several types of endothermal reactions that are extensively utilized on a commercial basis. This invention relates to the steam-hydrocarbon reforming reaction for the production of Hydrogen, Carbon Monoxide and synthesis gas. The steam hydrocarbon reforming process is conducted in externally fired multitubular reactors using fixed catalyst beds. As less endothermal reaction occurs the temperature of the reaction is increased. Finally, the tube temperatures increase and may approach that of the furnace itself. Such temperatures, if reached, are extremely damaging to the metal tubes and costly replacement of the expensive alloy tubes may be required. Even if the tube temperatures do not reach this severity, the operation must be shut down with increasing frequency, the catalyst must be changed and considerable operating time and production is thus lost.
However, it has been discovered that if heat exchange can be improved from the furnace through the tubewall and to the catalyst within the tube, the problem of loss of activity can be minimized. This is especially true if the catalyst is on specific support shapes and if the catalyst is of the type disclosed in co-pending application Ser. No. 638,505, filed: Dec. 8, 1975, and in U.S. Pat. No. 4,207,211 dated June 10, 1978. The most logical explanation for the increased efficiency of this structure is that because of the low length to diameter ratio, a larger fraction of the surface of the interior walls of the support's axially aligned gas passages receive almost direct radiation from the tubewalls. The direct radiation (temperature in the 1200.degree. F. to 2000.degree. F. range) is at almost vertical incidence to the interior wall surface and thus the direct absorption of radiation is enhanced. This assures efficient heat exchange from the furnace hot gases and a low delta T between this gas temperature and the catalyst temperature. This makes for the good utilization of the heat in the furnace and a high energy efficiency.
Pressure drop through the steam-hydrocarbon reformer tubes has historically been a severe problem and one which in the past has been .Iadd.a .Iaddend.frequent cause of catalyst failure. The unique catalyst structure of this invention overcomes much of this problem by providing more passages for the gas flowing through the tubes. These added channels or passages facilitate the gas transport through the tubes and thus decrease pressure drop.